Evaporative cooling system



Dec. 26, 1939. E. B. EVLETH EVAPORATIYE COOLING SYSTEM Filed March 23, 1958 Everett Evleth Snventor Bu Z Z Gttorneg Patented Dec. 26 1939 COOLING SYSTEM Everett B. Evleth, Bryn Mawr, Pa., assgnor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Deia,-

Ware Application March 23, 1938, Serial No. 197,689

13 Claims.

This invention relates to an air conditioning system and more particularly to a cooling sys' tem wherein the cooling of the air is eifectedby means of evaporating moisture therein. In many sections of the country having low relative humidity during the greater portion of the cooling season it has been found that the cooling of the air within a space may be effectively attained by means of spraying water into a stream of air drawn into the space from outdoors. Since the incoming air will usually have a, low relative humidity, the cooling ofthe air may be effected without raising the humidity to an undesirable value. It sometimes happens however that even in these sections of the country wherein such systems are found useful that the air being drawn in from outdoors Will have such a high relative humidity that the cooling of the air by evaporating moisture therein will produce uncomfortable conditions in the space and will be undesirable. A

One of the objects of my invention is to provide a novel control system for an evaporative cooling system wherein means are provided to prevent the operation of the cooling system when the hmumidity within the space becomes excessive.

Other objects'will become apparent upon a study of the specification, claims, and appended 30 drawing in which is illustrated a preferred form of my invention.

Referring more particularly to the drawing, a cooling chamber I having a fresh air inlet II and an outlet I2 may be positioned near the upper portion of the space which is to be cooled. Mounted within the chamber I0 is a fan I4 for drawing air into the chamber I0 through the.

` y inlet II and exhausting the air from the exit l2. A motor I5 is provided for causing the op- 40 eration of the fan I4 and may be controlled in any`suitable manner, not illustrated."

Located adjacent the inlet II of the chamber I0 is a filter I8 through which all the air entering the chamber I0 passes. A spray 20 is mounted in the chamber downstream from the filter I8 and a valve 2| controls the flow of water to the spray 20. Mounted just downstream from the spray is a setof eliminator plates 22 of any suitable well known construction for removing particles of moisture from the air, there being a sump 23 located beneath the plates 22 and provided with van outlet 24 through which the wat-er drains. Mounted near the outlet I2 is a set of da f rs 25 connected by means of links 26, 21, 5 and 28 to an arm' 29 operated by a motor 30 as (Cl. 23e-44)' wardly when cooling is desired within the space. 5

suitably mounted within the space being cooled is a thermostat 35, this thermostat including a bimetallic element 36 carrying an arm 31 which is caused to move by the bimetallic element' 36 in response to temperature changes within the space being cooled. Fixed contacts 38 and 39 cooperate with the arm 31, the arm 31 moving toward the left and into engagement with the contact 38 `in response to a temperature drop within the space and moving towards the right into engagement with the contact 39 inresponse to a temperature rise within the space.

Also mounted within the space being cooled is a humidity responsivedevice 40, which device may include an element 4I-which expands or contracts in response'to varying humidities with- `in the space. The upper portion of the element 4I is suitably fixed and the lower portion' of this element is 'connected to an arm 42 pivoted at 43, the arm 42 being biased in a direction to cause elongation of the element 4I by means of a spring 45. Fixed contacts 46 and 41 cooperate with the right end of the arm 42 which is suitably insulated by means of insulating material 48 from the rest of the arm. When the humidity Within the space rises the humidity responsive element 4I elongates and permits the right end of arm 42 to move into engagement with the contact 41 under the influence of the biasing spring 45. Upon a drop in humidity within the space, the element 4I contracts and causes the right end of arm 42 to mover upwardly and into engagement with the contact 46.

The motor causing operation of arm 29 may be a reversible two-position motor of any suitable. construction and may include a pair of selectively energized windings, one of these windings being energized upon connection of terminals 5l! and 5I and the otherV winding being energized upon connection of terminals 5I and 52. Power may be supplied to the motor 30 by means ofv conductors53 and 54 which may be connected to a suitable source of power, not shown. `When terminals 50 and 5I are connectedI together, the motor operates to rotate armV 29 to the position in which it is illustrated in the drawing, When terminals 5I and 52 are connected together, the motor -operates -to rotate vthe arm 29 in a clockwise direction to a position wherein the dempers 25 are moved to a position wherein the volume of air owing thereby is reduced to a minimum and the damper 32 is simultaneously moved upwardly so that the air leaving the chamber will not be directed downwardly.

Mounted on the left end of the arm 29 is a mercury switch 56 which includes a mercury element 51 and terminals 58, 59, 60, and 6|. This switch controls the operation of a motor 65 for controlling the position of the valve 2| in a manner` to be set forth. This motor may be similar in construction to the motor 30 and may include a winding energized upon connection of terminals 66 and 61, which causes the valve 2| to be moved to open position whereupon water is sprayed from the spray 20. A second winding energized upon connection of the terminals 61 and 68 causes the motor 65 to move the valve 2| to closed position when energized.

Operation With the parts in the position illustrated, the temperature within the space tobe cooled is relatively high whereas the humidity is not excessive. The terminals 50 and 5|- are connected together through the following circuit: from the terminal 5U through conductor 10, contact 39, the arm 31 of thermostat 35 and conductor 1| to the terminal 5|. The motor 30 has accordingly operated to move the arm 29 to the position shown, thus movvalve 2| is in open position, through the following circuit: from terminal 66 through conductor 15, the terminal 58 of switch 56, mercury element 51,

`terminal 59, conductor 16, contact 46, the right end of arm 42 of the humidity responsive device 40, and conductor 18 to the terminal 61 of motor 65. Water accordingly ilows through the spray 20 thus eifecting cooling of the air owing through the chamber I by means of evaporation.

When the temperature within the space drops to a desired value, the arm 31 of thermostat 35 moves into engagement with contact 38 thus connecting the'terminals 5| and 52 of motor 30 as follows: from terminal 52 through conductor 80, contact 38, arm 31, and conductor 1| to the terminal Motor 30 now operates to rotate the arm 29 in a clockwise direction thus moving the dampers 25 to minimum open` position and moving damper 32 upwardly, at the same time tilting the mercury switch 56 in the opposite direction wherein terminals 60 and 6| are connected together by the mercury element 51. Terminals 61 and 68 of motor 65 are now connected together as follows: from terminal 68 through conductors 82, 83, terminals 6| and 60 of switch 56, conductor 16, contact 46, arm 42, and conductor 18 to the motor terminal 61. Motor 65 now operates to close the valve 2| thus stopping the ow of water to the yspray 20 so that the air passing through the chamber I0 is no longer being cooled. The spray 20 will remain shut olf and the dampers 26 will remain closed until the temperature within the space again rises to a value wherein the arm 31 engages .the contact 39.

Assuming now that the parts are in the position illustrated wherein the thermostat 35 is calling for cooling, the spray 28 is turned on, the dampers 25 are open,'and damper 32 is deflecting the air downwardly into the space. Should the humidity within the space become excessive, the

humidity responsive element 4| will expand and permit the right end of arm 42 to move into engagement with the contact 41. This will cause the terminals 61 and 68 of motor 65 to be connected as follows: from terminal 68 through conductors 82, 85, contact 41, arm 42, and conductor 18 to the terminal 61 whereupon the motor 65 will operate to close the valve 2| and prevent further supply of water to the air passing through the chamber This circuit is independent of the mercury switch 56 and it will therefore be seen that as long as the humidity within the space remains excessive that the valve 2| will remain closed regardless of temperature conditions with-v in the space.

The system provides for a minimum supply of air to the space at all times for ventilation purposes and for a maximum supply of air to the Having described a preferred form of my invention many modications may become apparent to those skilled in the art and I wish it to be understood that my invention is limited only by the scope of the appended claims.

I claim as my invention:

1. In an evaporative cooling system, means for spraying water into the air to be cooled whereby the evaporation of the Water causes a reduction in the temperature of the air being cooled, temperature responsive means for causing operation of the spraying means .when the temperatureof the air being cooled rise's above a predetermined value and to interrupt said spray when the temperature drops below a predetermined value, and humidity responsive means also in control of the spraying means to interrupt operation thereof when the humidity of the air being cooled rises above a. predetermined value.

2. In an evaporative cooling system, means for spraying water into the air to be cooled whereby the evaporation of the water causes a reduction in the temperature of the air being cooled, valve means controlling the flow of water to the spraying means, means responsive to the temperature of the air being cooled in control of said valve means whereby water flows to said spraying means only when the temperature of the air being cooled is above a predetermined value, and means responsive to the humidity of the air being cooled also in control of said valve means whereby the valve means prevents the flow of water to the spraying means whenever the humidity of the air being cooled exceeds a predetermined value regardless of the temperature in said space.

3. I-n a cooling system, a cooling chamber in.

cluding a fresh air inlet and an outlet opening into a space to be cooled, volume damper means in control of said outlet, means for drawing air into said chamber through said inlet and exhausting said air through said outlet, means within said chamber for spraying water into the air passing through said chamber whereby the evaporation of the Water causes a reduction in ture in the space.

4. In a cooling system, a cooling chamber including a fresh air inlet and an outlet opening into a space to be cooled, volume damper -means in control of said outlet, means for drawing air into said chamber through said inlet and exhausting said air through said outlet, means within said chamber for spraying water into the air passing through said chamber whereby the evaporation of the water causes a reduction in the air temperature, valve means in control of said spraying means, temperature responsive means in control of said valve means and damper means whereby the damper means are opened and the valve means is opened to cause operation of the spraying means when the space temperature rises to a predetermined value, and humidity responsive means also in control of said valve means to prevent flow of water to the spraying means whenever the humidity in the ,space reaches a predetermined value. l

5. Ina cooling system, meansfor spraying water in the space to be cooled whereby the evaporation of the water-causes a reduction in the temperature of the air in said space, and means responsive to the temperature and humidity in said space for causing operation of the spraying means only when the temperature in the space is above a predetermined value and the humidity in the space is below a predetermined value.

6. In a cooling system, means for causing a flow of outdoor air into a space to be cooled, means for spraying water into said air ow whereby theevaporation of the water causes a .reduction in the temperature of the air in said space, and means responsive to the temperature and humidity in said space for causing operation of the spraying means only when the temperature in the space is Aabove a predetermined value and space, means responsive to the temperature and humidity in said space for causing operatiomof the spraying means only when the temperature in the space is above a predetermined value and the humidity in the space is below a predetermined value, and means responsive to the temperature of the air in the 'space for controlling the rate of ow of the air into the space.

8. In a.cooling system, means for causing a ow of outdoor air into a space to be cooled, means for spraying water into said air flow whereby the evaporation of the water causes ja reduction in the temperature of the air in said space, means responsive to the temperature and humidity in said spaceL foi' causing operation of the spraying means only when the temperature in the space is above a predetermined value and the humidity in the space is below a predetermined value, and means responsive to the temperature of the air in the space for controlling the rate and direction of the air flow into the space.

9. In a cooling system, a cooling chamber including a' fresh air inlet and an outlet opening into a space to be cooled,` volume damper means in control of said outlet, means for drawing air into said chamber through said inlet and exhausting said air through said outlet, means within said chamber for spraying water into the air passing through said chamber whereby the evaporation of the water causes a reduction in the air temperature, means responsive to the.

temperature of the space being cooled for causing movement of the damper means to open position and for causing operation of the spraying meanswhen the space temperature exceeds a predetermined value, means responsive to the humidity in the space being cooled for preventing operation of the spraying means whenever the humidity in the space exceeds a predetermined value regardless of the temperature in the space, and means for causing the air leaving said chamber to be directed downwardly as the volume of the air leaving said chamber increases.

10. In an evaporative cooling system, a cooling chamber, means for circulating fresh -air through said chamber and a space to be cooled, damper means controlling the flow of air through the chamber, means for controlling the position of said damper means, meansvresponsive to the temperature of the space'being cooled in control of said position controlling means whereby the damper means are in open position when the temperature in the space is above a predetermined value and are moved toward closed position when the temperature in the space is below a predetermined value, means for spraying water into the cooling chamber, valve means in control vof said spraying means, and means for moving the valve means to open position only when the damper means are in open position and Vthe humidity in the space is below a predetermined value.

11. In an evaporative cooling system, a cooling chamber, means for circulating fresh air through said chamber and a space to be cooled, damper means controlling the flow oi.' air through the chamber, means for controlling the position of said damper means, means responsive to'the 50 temperature of the space being cooled in control of said position controlling meanswhereby the damper means are in open position when the temperature in the space is above a predetermined value and are moved toward closed position when the temperature in the space is below a predetermined value, a control device operated by the position controlling means for the Idamper means, means for spraying water into the cooling chamber, valve means in control of said spraying means, vmeans responsive to the humidity in the space being cooled, and means controlled by the control device -and the humidity responsive means for controlling said valve means for causing the opening of said-valve means only when the humidity in the space is below a predetermined value. vand the damper means are in open position.

12. In an evaporative cooling system, a cooling chamber, means for circulating fresh air through said chamber and a space to be cooled, damper means controlling the flow of air through said chamber, a motorl for controlling the position of saiddamper means, means responsive to the temperature of the air in said space in control of said motor, means for spraying Water into the air passing through said chamber, valve means in control of said spraying means, a switch operated by said motor having a first circuit controlling position When the damper means are in open position and having a second circuit controlling position When the damper means are moved towards closed position, a motor in control of said valve means, means responsive to the humidity of the space being cooled, circuit connections for causing said second motor to move the valve means to c losed position when said switch is in the second circuit controlling position, and circuit connections controlled by said humidity responsive means for causing said second motor to move the valve means to open position only when the humidity in the space is below a predetermined value and said switch is in the first circuit controlling position.

13. In an evaporative cooling system, spray means for reducing the temperature of the air in a space by evaporation of water, valve means controlling the operation of said spray means, electrical means in control of said valve means, means responsive to the humidity of the space, said humidity responsive means including switching means movable to a first position in response to a low relative humidity in the space and movable to a second position in response to a high relative humidity in the space, means responsive to the temperature of the space, said temperature responsive means including switching means movable to a first position in response to a high temperature in the space and movable to a second position in response to a low temperature in the space, circuit connections controlling said electrical means, said circuit connections includingsaid switching means and means operative when both switching means are in the rst positions to cause the electrical means to open the valve and operative when either of the switching means is in the second position to cause the electrical means to close the valve.

EVERETT B. EVLETH. 

